Method of manufacturing axle assemblies

ABSTRACT

An axle assembly includes an axle member, a flange, and a spindle. The flange is provided with a central bore. An end portion of the spindle extends through the central bore of the flange to contact an end of the axle member. A central portion of the spindle contacts a surface of the flange. Separate weld joints are formed between the axle assembly components at the two contact areas. The welding flash around the outer circumference of the weld may be removed to allow for visual inspection. A preferred method of manufacturing the assembly is by a friction or inertia welding process.

This is a division of application Ser. No. 641,705, filed 8/17/84, nowU.S. Pat. No. 4,659,005, issued 4/21/87.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates generally to axle assemblies and, moreparticularly, to certain improvements in welded axle assemblies.

The manufacture of axles for trucks, trailors, and other applicationstypically involves a combination of welding, machining, and forgingoperations. For example, a known method involves forging (swaging) atube or banjo housing on its ends to form a single piece axle/spindleassembly. A flange, such as might be used for braking or wheel mounting,is subsequently attached to the assembly, usually by welding. Anothertechnique involves welding a spindle directly to the ends of a roughforged or machine finished axle tube, followed again by subsequentattachment of the flange. In still another method, two formed halves arejoined by welding to produce an axle housing. The spindles and flangesare then attached to the housing by separate welding operations.

A technique for manufacturing an axle assembly by a friction weldingprocess is described in U.S. Pat. No. 4,223,825 to Williams. This methodinvolves welding a spacer tube to a spider, machining the inner bore ofthe spacer tube to remove material produced by the welding operation,placing the spider/spacer subassembly on the end of the axle tube, andconcurrently welding, by friction or inertia welding techniques, aspindle to the spacer and the axle tube.

With the exception of the Williams technique, all of the above discussedmethods require a forging operation to directly form the spindle on theaxle, or, in the case of separately attached spindles, to reduce theaxle end diameter to the spindle diameter for purposes of forming thewelded joint. Following attachment or formation of the spindle,subsequent machine or welding operations are required to attach theflange to the spindle/axle assembly. An alternative which reduces orsimplifies these manufacturing steps, while providing a structurallyadvantageous product, is the subject of a related patent applicationSer. No. 632,224 by the present inventor entitled "Axle AssemblyArrangement" filed on July 19, 1984 (now abandoned). To the extentappropriate, pertinent disclosure from that application is herebyincorporated by reference into the present application.

In the method described by Williams, no subsequent welding operation isrequired to attach the flange since the spindle/axle and the flange(i.e., the spider/spacer subassembly) are joined in a single weldingoperation. Referring to FIG. 6 of the Williams patent, it can be seenthat a single weld 16 is formed to simultaneously join the threecomponents. However, also apparent from this figure is that only theouter surface of weld 16 can be visually inspected when the axleassembly is complete. The weld which join end 25 of the axle beam to endportion 32 of the spindle cannot be visually examined. This is also truefor the radial inner portion (29) of the weld joins inner portion 30 ofthe axle beam to outer surface portion 31 of the spindle.

Accordingly, an object of this invention is to provide an improved axleassembly arrangement.

Another object of this invention is to provide an axle assemblyarrangement which provides for visual inspection of the individual weldjoints formed between the axle components.

Yet another object of this invention is to provide an axle assemblyarrangement which is compatible with efficient axle manufacturingtechniques, such as friction and inertia welding processes.

These and other objects are attained in an axle assembly arrangementwhich comprises a spindle, a flange, and an axle member. The spindle hasan end portion which is generally circular in cross-section and has afirst outer diameter, a central portion which is also circular incross-section and which has a relatively larger outer diameter, and aconnecting transition between the two portions. The connectingtransition is preferably a step-like transition which forms a radiallyextending face on the central portion which is subsequently welded to asurface of the flange. The flange has a central bore which is coaxiallyaligned with, and spaced apart from, an end of the axle member. The endportion of the spindle extends through the central bore of the flange,allowing the radially extending face of the central portion of thespindle to abut the surface of the flange which faces away from the endof the axle member. An end surface of the end portion of the spindleabuts the end of the axle member. A first weld joint is formed betweenthe abutting surfaces of the central portion of the spindle and theflange. A second weld joint is formed between the abutting surfaces ofthe spindle end portion and the axle member.

A preferred method of manufacturing the axle assembly of the presentinvention includes the steps of locating an axle member in a firstworkholding means, locating a flange having a central bore in a secondworkholding means such that the central bore of the flange is alignedwith and spaced apart from an end of the axle, locating a spindle in athird workholding means, positioning the third workholding means suchthat an end portion of the spindle extends through the central bore ofthe flange and such that the central portion of the spindle abuts thesurface of the flange, welding the central portion of the spindle to thesurface of the flange, and welding the end portion of the spindle to theend of the axle. The two welding steps are preferrably performedconcurrently. An especially preferred method includes the additionalstep of removing the welding flash produced by the welding operationfrom around an outer circumference of at least one weld to allow for avisual inspection of the weld. The welding steps are preferrablyperformed by friction or inertia welding techniques.

Other objects and advantages of the present invention will be apparentfrom the following detailed description of a preferred embodiment, whenconsidered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a spindle, a flange and an axle member mounted inrespective workholding means prior to assembly, in accordance with thepresent invention.

FIG. 2 shows the spindle, flange and axle member of FIG. 1 afterformation of the weld joints to complete the manufacture of the axleassembly.

FIG. 3 shows the arrangement of FIG. 1 for an axle assembly comprising ahollow, tubular spindle and axle member.

FIG. 4 shows the arrangement of FIG. 2 for an axle assembly comprising ahollow, tubular spindle and axle member.

FIG. 5 shows a solid axle assembly mounted on a double-ended weldingmachine.

FIG. 6 shows a hollow axle assembly mounted on a double-ended weldingmachine.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the components of an axle assembly prior to formation ofthe weld joints in accordance with the present invention. The componentsinclude axle member 10, flange 12, and spindle 14. Axle member 10 has anend surface 16 which faces the other axle components. Although axlemember 10 is depicted in FIG. 1 as a solid member, a tubular (i.e.,hollow) axle member may be used as well. Axle member 10 is held inposition by stationary workholding means 18 which, in the preferredmethod described below, is the stationary tailstock member of a frictionor inertia welding apparatus.

Flange 12 is provided with a central bore 20 and is held in position bya second workholding means 22. In this preferred embodiment, workholdingmeans 22 is a stationary attachment to the tailstock of the frictionwelding apparatus and serves to align and hold flange 12 in position,with respect to axle member 10 and spindle 14. Flange 12 is positionedsuch that central bore 20 is coaxially disposed with respect to commonlongitudinal axis 24 of axle member 10 and spindle 14. Flange 12 isfurther positioned in workholding means 22 such that a first flangesurface 26, which faces end 16 of axle member 10, is spaced apart fromend 16 by a distance D, as indicated in the figures. A second flangesurface 28 faces away from end 16 of axle member 10 and towards spindle14. Flange 12 preferrably serves as a brake flange, or alternatively, awheel mounting flange when attached to the axle assembly.

Spindle 14 has an end portion 30, a central portion 32 and a connectingtransition between portions 30 and 32, indicated generally by referencenumeral 34. End portion 30 has a generally circular crosssection and anouter diameter which is slightly smaller than central bore 20 of flange12. Central portion 32 also has a generally cylindrical cross-sectionand an outer diameter which is substantially larger than the outerdiameter of end portion 30 and central bore 20. Transition 34 ispreferrably a steplike transition, as shown in FIG. 1. This stepliketransition forms a radially extending surface or face 36 on the side ofspindle central portion 32 which faces flange 12. As will be describedbelow, when spindle 14 is positioned for welding to flange 12 and axle10, face 36 interfaces with a portion 38 of flange surface 28,immediately surrounding central bore 20. The relative diameters offlange central bore 20 and spindle central portion 32 determine the areaof interface between face 36 and surface portion 38 as indicated byreference numeral 42 in FIG. 2.

Spindle 14 is shown in FIG. 1 mounted in a third workholding means 40.Workholding means 40 is preferrably the rotatable headstock of afriction or inertia welding apparatus. Although spindle 14 is depictedin FIG. 1 as a solid member, a hollow or tubular spindle member may beused as well.

FIG. 2 shows the axle components of FIG. 1 after completion of thewelding steps to form the axle assembly. As can be seen in FIG. 2,workholding means 40 is advanced along longitudinal axis 24 untilspindle end portion 30 contacts end surface 16 of axle member 10 andface 36 of central portion 32 contacts flange surface portion 38. Thelongitudinal dimension of end portion 30 and the position of axle member10 in workholding means 18 are preferably selected so that theserespective contacts, and the resulting welding operations, take placesimultaneously. Alternatively, spindle 14 may be welded to flange 12 ina first welding operation, followed by the welding of spindle 14 to axlemember 10 in a second operation. The weld joint formed between spindleend portion 30 and axle member end surface 16 is indicated generally byreference numeral 44 in FIG. 2. The weld joint formed between spindlecenter portion 32 and flange surface portion 38 is indicated generallyby reference numeral 46 in FIG. 2.

The structure and method described above and illustrated in FIGS. 1 and2 result in the formation of weld joint 44 in a first generally vertical(as viewed in FIG. 2) plane and formation of weld joint 46 in a secondgenerally vertical plane which is spaced apart from the first plane bythe distance D plus the thickness of flange 12. So positioned, thewelding flash around the outer circumference of both weld joints can beremoved, if desired. Removal of the flash allows for a visual inspectionof both weld joints 44 and 46.

As noted, a preferred method of forming weld joints 44 and 46 is by afriction or inertia welding process. The positioning and alignment ofthe axle assembly components, as described above, is readilyaccomplished using a friction welding apparatus. Welds 44 and 46 maythen be individually, or concurrently, formed.

FIGS. 3 and 4 illustrate the method and structure described above for anaxle assembly comprising a tubular spindle and axle member. For purposesof clarity, the same reference numerals used in FIGS. 1 and 2 areassigned to corresponding structures in FIGS. 3 and 4.

FIGS. 5 and 6 show, respectively, solid and hollow axle assemblies asmanufactured on a double-ended friction welding machine. The referencenumerals in these figures have been increased by one hundred, butotherwise correspond to the numerals used in FIGS. 1-4. Using thedouble-ended welding machine, flanges 112 can be mounted in workholders122 in a preferred relative angular orientation and then welded tospindles 114 without disturbing the orientation of either flange.

Although the invention has been described in terms of a detailedpreferred embodiment, it is to be understood that this description is tobe taken by way of illustration and example only, and not by way oflimitation. The spirit and scope of the invention is to be limited onlyby terms of the appended claims.

What is claimed is:
 1. An axle assembly for a vehicle comprising:an axlemember having an outer surface on an end thereof; a flange having acentral bore coaxially aligned with and axially spaced apart from theend of the axle member, and having a first surface facing away from theend of the axle member; and a spindle having an end portion whichextends through the central bore of the flange and which is welded tothe outer surface on the end of the axle member, and said spindle havinga central portion which is welded to the first surface of the flange,wherein the central portion and end portions of the spindle aregenerally circular in cross-section and wherein an outer diameter of thecentral portion is substantially larger than an outer diameter of theend portion.
 2. The axle assembly according to claim 1, wherein atransition from the central portion to the end portion of the spindle isa step-like transition and, wherein a radially extending face of thestep-like transition is welded to the first surface of the flange. 3.The axle assembly according to claim 1, wherein said axle member is asolid member.
 4. The axle assembly according to claim 1, wherein saidspindle is a solid member.
 5. The axle assembly according to claim 1,wherein said axle member is a hollow member.
 6. The axle assemblyaccording to claim 1, wherein said spindle is a hollow member.
 7. Theaxle assembly according to claim 1, wherein said flange is a brakeflange.
 8. The axle assembly according to claim 1, wherein said flangeis a wheel-mounting flange.